I'm trying to replace my shower hose with a new one. The problem I am having is that I cannot seem to able to turn the threaded connector at the elbow end of the hose. There is no problem unscrewing at the showerhead end, I have tried both locking and waterpump pliers for removal. Has any anyone got any ideas on how to remove it?

Apply a bit of heat. If its a metal connector then differential expansion should loosen it. If its a plastic one it doesn't matter as you are replacing it anyway LoL. If its plastic you could also cut through it lengthways if you can get the correct angle.